This research project is intended to gain understanding of the interactions between the cellular elements of the nervous system and the modification of these interactions by previous activity. Experiments are proposed utilizing electrophysiological, fluorometric and morphological techniques to study the functional interdependence of neurons and glia in Necturus and crustacea. Processes under investigation include the proposed role of glia in regulating extracellular concentrations of ions, amino acids and possible transmitter compounds. Further studies on the metabolic responses of glia to alterations in the ionic environment and on the membrane characteristics of glia are also proposed. BIBLIOGRAPHIC REFERENCES: H. Bracho, P.M. Orkand, and R.K. Orkand. A further study of the fine structure and membrane properties of neuroglia in the optic nerve of Necturus. Journal of Neurobiology 6, 395 (1975). Neuromuscular junctions in the buccal mass of Aplysia: Fine structure and electrophysiology of excitatory transmission. Journal of Neurobiology 6, 531 (1975). P. M. Orkand and R. K. Orkand